1) Field of the Invention
The present invention relates to technology for digital content editing.
2) Description of the Related Art
In recent years, a number of Digital Rights Managements (DRMs) as a technique for protecting the copyright of a digital work are developed. In particular, commercial digital contents such as movies and music are developed in such a manner that strong copyright protection is advantageous for content providers as typified by Digital Versatile Discs (DVDs).
A copyright protecting function in the techniques provides a very rigid, strong mechanism to address a strong demand for copy prevention of a digital content and limits the flexibility of the users on digital contents more than analog contents.
The Japanese Copyright Law includes the regulation of so-called “fair-use” that a work can be used, for example, copied or cited, for private use without permission of the author. However, as described above, the flexibility of the users on digital works is restricted due to the copy protection. Consequently, the user cannot copy or cite a digital work even for private use and the fair-use on digital works is in increasing demand.
On the other hand, under present circumstances, little attention is paid to the copyright protection on non-commercial contents such as business documents, product catalogs, personal homepages, and e-mails which are reused or subjected to secondary process on a daily basis, so that contents cannot be safely distributed.
Under such circumstances, the international standardization activities such as ISO/IEC 21000 (MPEG 21) aiming at distribution and management of digital contents in various forms are underway. In MPEG21, a language (DIDL: Digital Item Declaration Language) for expressing a multiple content constructed by combination/coupling of a plurality of contents is standardized. It enables a multiple content constructed by a plurality of contents as components to be handled. Further, Rights Expression Language (REL) enabling flexible license description is standardized. A supporting method for describing a license with the REL, for example, is proposed in United States Patent Application Publication No. US2003/0125976.
Japanese Patent Application Laid-open No. 2002-109103 discloses a technique of dividing a content into parts, distributing the parts, allowing the parts to be reused as materials, reasonably charging the user for the use of the material contents, and assuring payment to the usage of the contents.
When a multiple content is to be distributed and reused, however, each of the components of the multiple content may be singly distributed and reused as a content or may be combined with another content and the resultant is used. In such a case, when a component is singly used, context information such as positioning of a particular component in a whole content and a relation with another component may be lost. Then, the original intension of the author might be expressed wrongly or transmitted as nonsense information.
When distribution of digital contents that can be reused more easily is considered, such a situation becomes a big problem that prevents sound reuse of a content.
In the DIDL of MPEG 21, the structural information of a multiple content can be expressed. However, when a multiple content is divided and parts of the content are distributed, the parts cannot be reconstructed to the original structure. In the technique of United States Patent Application Publication No. US2003/0125976 using REL of MPEG21, a use license can be set for each of components of a multiple content but a license including the relation among contents cannot be described.
In the technique of Japanese Patent Application Laid-open No. 2002-109103, even when a content is singly distributed, the right of the author to receive proper consideration can be protected but context information initially set by the author cannot be protected.